In the process of manufacturing the thin film transistor liquid crystal display (TFT-LCD), via holes need to be formed in both the interior and the peripheral regions of the display panel. Since via holes and their peripheral areas form a rugged surface, the orientation layer, e.g. polyimide (PI) film, would be unevenly diffused when being coated, thereby seriously impacting the display quality of images in local display areas. For example, PI dark Mura arises in the periphery region of the display panel, and traces are presented due to the uneven brightness of the display.